Discoverer 28 (Corona Mission 9021 / KH-2 7), a CIA/NRO film-return photoreconnaissance satellite and the final KH-2 flight, launched on a Thor DM-21 Agena-B from Vandenberg on 4 August 1961. Second-stage control failed during ascent, so the payload never reached orbit.
- Outcome
- Failure
- Payload to orbit
- Did not reach orbit
- Flight
- 13th
- of 40 Thor DM-21 Agena-B flights
- Date and time
- 4 August 1961, 00:01 UTC
- Rocket
- Thor DM-21 Agena-B
- Builder
- McDonnell Douglas
- Launch site
- Space Launch Complex 1W, Vandenberg SFB, CA, USA
- Payload
- Unknown
- Launches in 1961
- 26th of 50